Push rod for rocker arm actuation

ABSTRACT

The present invention provides an improved push rod for actuating poppet valves in internal combustion engines. The improved push rod provides a vibration dampening beam member to alter push rod vibration frequency spectrum, levels and amplitude introduced through push rods to valve systems. Reducing push rod vibrations and amplitude improve valve system and engine performance.

CROSS-REFERANCE TO RELATED PATENT APPLICATION

This is a non-provisional application relating to and claiming the benefit of U.S. Provisional Patent Application Ser. No. 60/755,455, Filed Jan. 3, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of internal combustion engines pertaining to poppet valve operating systems having rocker arms actuated by push rod and cam, particularly a push rod beam member providing means to dampen vibration by an elastomeric component and outer cover embodiments.

2. Description of Background Information

Internal combustion engines having poppet valve systems actuated by push rods that operate generally at high engine speed, or having aggressive valve actuation, commonly experience levels of induced vibration and dynamic motions in the valve system. Such vibrations adversely affect the valve system and engine performance. The primary dynamic responding members of the valve system assembly are the push rod, rocker arm, valve and valve spring assembly. These primary members as a consequence of high engine speed and aggressive valve actuation requirements initiate vibrations that transmit and reinforce and amplify dynamic forces affecting the valve system. The push rod and valve spring are arguably the principle members where vibrations and dynamic response need control improvement. The invention provides a means to control and dampen push rod vibration frequencies and force amplitude in the field of internal combustion engine poppet valve systems.

The push rod generally being a beam having a long slender tube shape momentarily deforms from cam acceleration rates as opening forces are required to overcome mass effects of the rocker arm, the valve and valve spring's closing force. Push rod deflecting conditions also reoccur on the closing cycle as the spring returns the components to the closed position with inertia force that deflects the push rod. These cyclical forces loading the push rod may occur at over 70 cycles per second on high-speed valve systems. Therefore on valve systems having aggressive valve lift rates, the initial opening inertia cycle force being high commonly deflects the push rod beam body inducing vibrations and dynamic force amplification to the push rod and valve system components. A means to dampen push rod vibrations and amplitudes embodying elastomeric component and rigid outer covering is disclosed.

SUMARY OF THE INVENTION

In one form of the present invention there is provided a tubular push rod beam for opening and actuating poppet valves for internal combustion engines. A push rod is provided. A elastomeric component is bonded to the outer surface of the tubular push rod load carrying beam. In another form of the present invention a push rod is provided having an outer cover bonded to the elastomeric component. The push rod assembly includes at each end a ball-socket connection. First ball-socket registers in a socket of a separate system lifter that transmits opening forces actuated by the cam to the push rod. Second ball-socket registers at opposite push rod end to a connection at a separate rocker arm to open and close a poppet valve.

The elastomeric being bonded to the push rod tubular beam has prescribed thickness and elastomeric characteristics to provide dampening push rod vibrations. The outer cover provides added vibration dampening and deflection control by bonding to and incasing the elastomeric dampening medium. Reduction in vibration amplitude can be important, particularly at or near resonant frequencies. Vibration spectrum modification is an important objective. Resulting improvements in valve train dynamic behavior are sufficient to make notable engine performance improvement.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute a part of this specification and include the embodiment of this invention.

FIG. 1 is a side elevation view of a complete push rod valve system.

FIG. 2 is a side elevation view of the push rod assembly illustrating a system of one embodiment of the present invention.

FIG. 3 is an enlarged transverse section VIEW-A, illustrating one embodiment of the present invention.

FIG. 4 is a cross section view of the push rod assembly illustrating component embodiment of the present invention taken at cut line 4-4 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERED EMBODEMENTS

In one specific embodiment of the present invention there is provided an improved push rod for actuation of rocker arms and poppet valve actuation for internal combustion engines. The improved system embodies a push rod having a vibration dampening elastomeric component bonded along the longitudinal length to the diameter of a tubular push rod.

In another specific embodiment of the present invention there is provided a push rod having a vibration dampening elastomeric component bonded along the longitudinal length having an added tubular outer component cover bonded to the elastomeric. The outer cover generally being thin metal tubing. The outer covering component is not limited to metal tubing; in certain applications materials such as high strength tape may be tensioned wrapped to provide resistive reaction to vibration force transmission. Embodiment of the cover provides a further means of absorbing vibration energy and amplitude.

A detailed description of a push rod poppet valve system is presented with reference to FIG. 1 of the drawings. There depicted a push rod system for poppet valve actuation composing a cylinder head assembly 1, having a mounted pivoting rocker arm assembly 2, a valve spring and retainer assembly 3 in phantom view, and poppet valve 4. Continuing with FIG. 1, engine block 5 supporting valve lifter 6, being actuated for valve opening and closing by cam 7. The push rod 8 having a ball-socket at each end connects first ball-socket from valve lifter 6 end to opposite end connecting at the second ball-socket to the rocker arm assembly 2. The ball-socket connections provides for misalignment and movement between lifter 6 connections and rocker arm lash adjustment screw 9. There are other push rod systems not illustrated that vary in the connection detail to the push rod, generally rocker arms not requiring adjustment screw 9, such as systems using hydraulic lifters to accommodate valve lash or using shims. Other systems may alter, exchange the method of ball-socket connection; occasionally the push rod is fitted with a socket end rather than a ball end. Push rods having the vibration dampening embodiment of the present invention are generally convenient for replacing existing push rods with out making system changes, as the push rod dimensions remain similar.

FIG. 2, at VIEW-A disclose specification of the first specific embodiment of present invention. The inner details of the push rod beam 8 is disclosed in FIG. 3, illustrating cross-section VIEW-A. Referring to FIG. 3 the push rod beam 10 defines the load carrying member being tubular. Diameters generally range from 0.375 to 0.500 inch and have specified wall thickness. Push rod beam 10 is generally made from high strength alloy steel of the SAE 4130 and 4340 types. Other materials for push rod beams are aluminum and titanium metals or materials providing proper strength and stiffness characteristics. Push rod beam 10 wall thickness is determined from column load analysis. Push rod beam 10 is depicted as a constant diameter through out the longitudinal length. There are applications were the push rod beam is tapered at each end, tapering from near center to each ball-socket end. Oil passage 13, is defined by the required wall thickness of push rod beam 10 and extends longitudinal axially through the beam 10 and continues through the socket connections. The oil passage purpose is transferring oil from lifter 6 through adjusting screw 9 connection to lubricate rocker arm 2 and valve system. The dimensions and material applications disclosed are to illustrate a typical application to meet performance and design parameters applicable to the elastomeric vibration damping push rod.

Continuing with FIG. 3 at VIEW-A a section view disclose specification for elastomeric component 11. Elastomeric component 11 depicted vulcanized to push rod beam 10, a first embodiment. And, also to cover 12 a second embodiment, to be discussed. Elastomeric component 11 is an innovation of the invention being an elastodynamic means to absorb and dampen vibrations. Based on the principle that a mass of rubber like elastomer is deformed absorbing and dampening vibration energy as a result of molecular friction within the elastomer. The elastomeric component 11 compound is selected for vibration damping properties and may be determined from engine testing data relating to vibration measurements. Elastomeric component 11 having a thickness on the order of 0.050 inch or greater is bonded by vulcanization to push rod beam 10.

Continuing with FIG. 3 cover 12 a second specific embodiment of the present invention. Cover 12 is vulcanized to elastomeric component 11. The function of the cover 12 innovation is to react by dampening dynamic vibration amplitude transmitted through elastomeric 11 from vibrations and deformations induced from the push rod beam 10. Cover 12 preferably being metallic generally having a thin wall thickness of approximately 0.020 inch for the represented application. The thin wall embodiment provides slight elastic deformation to respond and dampen vibration pressure profiles in combined action with the elastomeric. Material chosen for cover 12 considers elastic modulus, preferably a metallic alloy tubing of selected temper and thickness. A cover 12 having a non-metallic second embodiment is disclosed, consisting of a wrapping of non-metallic specialty material in tape form, wrapped under tension, resulting in a compressive force application to the elastomeric component. The cover 12 outer surface may have a tapered form to dampen certain vibration and stress profiles. For Example, havening a thicker diameter or wall thickness at the longitudinal center and tapering to a smaller diameter or wall at the beam 10 ends.

Continuing with FIG. 4, cross section 4-4 taken from FIG. 2, a pictorial cross section view to illustrate specification clarity. Consisting of the push rod beam 10, illustrating a diameter of 0.375 inch, having a wall thickness of 0.125 inch and oil passage 13 of 0.125 inch diameter. The elastomeric component 11 is illustrated having a thickness of 0.050 inch. And, an outer metallic cover 12 is illustrated having a thickness of 0.020 inch. Some applications of the vibration resistant push rod require clearance where cylinder head structure is close. In such cases beam tapering at the ends is applicable. Reducing elastomeric covering a minimal distance from the push rod ends is also appropriate.

Manufacturing the push rod elastomeric is disclosed for one embodiment of the present specification that having push rod beam 10 and component 11. Referring to FIG. 3 and FIG. 4. Push rod beam 10 is positioned with commercially available tooling to mold and form the elastomeric component with controlled and accurate wall thickness. Elastomeric viscous material is forced into a thickness forming cavity. In another specific embodiment of the present invention cover 12 is provided. Cover 12 is vulcanized in an assembly fixture that locates both cover 12 and push rod beam 10 dimensionally and concentric. The fixture having locating collars at each end of the push rod beam 10 centering concentric with the outer cover 12 providing the necessary cavity width for the elastomeric. After fixturing, elastomeric viscous material is forced into the cavity. Elastomeric is then cured and hardened to the appropriate elastic requirements and adhesion to the inner tube and outer tubular components. The dimensions and material applications disclosed here are to illustrate a probable application to meet performance and design parameters applicable to the elastomeric vibration damping push rod. Assembly and manufacturing method choice may vary with each push rod design requirements.

Although preferred embodiments have been specified in the detailed description, there are system variations and combinations of the disclosed embodiments not shown that may be used. Combinations having beam tapering and elastomeric sections having varied hardness and dampening are applicable. The specified embodiments of the present invention are especially noted to be applicable to requirements of the general field of internal combustion engines and poppet valve operation. 

1. A push rod system for internal combustion engines comprising: a push rod load carrying beam; a elastomeric component vulcanized to the beam; a first ball-socket connection at a first end utilized to connect a lifter means operated by an engine cam; a second ball-socket connection at the opposite end to connect to an engine rocker arm and valve assembly; said push rod beam being a axial load carrying member having tubular form of metal structure; said elastomeric component vulcanized bonded along the longitudinal beam length being a vibration absorbing component; said elastomeric being homogeneous texture component vulcanized bonded onto said beam member.
 2. The system of claim 1 wherein said push rod beam has an outer tubular cover along the longitudinal length vulcanized bonded to inner elastomeric comprising; said outer cover being tubular and positioned longitudinally and concentric to said push rod beam member providing a cavity for a elastomeric component; said elastomeric being homogeneous texture component within a cavity vulcanized bonded to said push rod beam and to the outer cover. 